This invention is related generally to dispensing apparatus and, more particularly, to apparatus for dispensing flexible sheet material including apparatus for controlling the amount of material dispensed.
Dispensers: for flexible sheet material, such as paper toweling and the like, are well known in the art. These dispensers typically discharge the sheet material from one or more rolled webs stored within the dispenser. The sheet material is dispensed when the user grasps the sheet material tail, which extends outwardly from the dispenser, and pulls the tail away from the dispenser.
Within the dispenser, the web of sheet material is typically drawn through a nip and over a roller which rotates as the web is pulled by the user. Rotation of the roller typically operates a cutting mechanism which completely or, more typically, partially cuts through the web. This cut ting action separates the web into sheets of par predetermined length. The cutting mechanism may, for example, comprise a movable blade mounted within the roller as in U.S. Pat Nos. 5,441,189 (Formon et al.), 4,621,755 (Granger) and 4,122,738 (Granger) or rotating knife and slot rollers as in U.S. Pat. No. 3,575,328 (Jespersen et al.).
An important issue affecting these types of dispensers involves controlling the dispensing cycle and the amount of material which is dispensed. The dispenser must discharge sufficient web material for the user yet at the same time must not discharge excessive amounts of material thereby unduly depleting the stored web material.
Avoidance of excessive material discharge is a particular problem confronting dispensers which cut only partially through the web since, without appropriate control, such machines can allow multiple sheets of material to be dispensed in a single pull by the user. Further, the dispenser must be controlled so that at the end of each dispensing cycle the dispenser is positioned in a ready position for the start of the next dispensing cycle.
A variety of dispenser stop mechanisms have been developed in an effort to address these issues. However, these mechanisms have certain disadvantages. For example, U.S. Pat. No. 5,441,189 (Formon et al.) utilizes a stop mechanism which relies on a spring, rather than a positive stop mechanism, to gradually arrest movement of the roller and to tear the partially perforated sheet material. The spring further serves to orient the roller for the next dispensing cycle. However, the lack of a positive stop mechanism limiting the dispensing to a single dispensing cycle may, undesirably, permit the user to discharge excessive amounts of material.
The stop mechanisms in U.S. Pat. Nos. 4,621,755 (Granger), 4,122,738 (Granger) and 3,575,328 (Jespersen), while limiting dispensing to a single cycle, comprise complex mechanisms with many moving parts. Such arrangements are disadvantageous because the large numbers of moving parts unduly add to the cost of manufacture and assembly and increase the likelihood that the dispenser may fail during operation.
It would be a significant improvement in the art to provide dispenser apparatus with an improved stop mechanism that would positively limit the amount of material dispensed in a dispensing cycle, position the dispenser for dispensing at the end of each cycle and which would include an elegant design requiring fewer parts resulting in lower costs of manufacture and increased reliability of operation.
It is an object of this invention to provide an improved dispenser apparatus and apparatus stop mechanism overcoming some of the problems and shortcomings of the prior art.
Another object of this invention is to provide an improved dispenser apparatus and apparatus stop mechanism which positively stops drive roller rotation.
Another object is to provide an improved dispenser apparatus and apparatus stop mechanism which positively controls the amount of web dispensed.
A further object of this invention is to provide an improved dispenser apparatus and apparatus stop mechanism which limits excessive dispensing of web material.
Still another object of the invention is to provide an improved dispenser apparatus and apparatus stop mechanism with few moving parts.
It is also an object of this invention to provide an improved dispenser apparatus and apparatus stop mechanism which has a rugged design yet is economical to manufacture.
Yet another object of this invention is to provide an improved dispenser apparatus and apparatus stop mechanism which reduces waste of web material.
An additional object of this invention is to provide an improved dispenser apparatus and apparatus stop mechanism which aids the user in easily removing a single web sheet of predetermined length from the dispenser.
These and other objects of the invention will be apparent from the following descriptions and from the drawings.
The invention is directed to improved apparatus for dispensing flexible web material from one or more rolls including stop apparatus for reliably and simply controlling the amount of web material dispensed. The apparatus includes a frame for rotatably supporting drive and tension rollers and drive and tension rollers mounted thereon. A nip is formed at the junction of the drive and tension rollers. Web material is fed from a roll stored with respect to the dispenser, through the nip and out of the dispenser through a discharge opening. The user pulls the web material tail from the dispenser and that action provides the energy needed to both dispense the web material and to control such dispensing using the improved stop.
In broad terms, the improvement comprises apparatus for controlling the amount of web material dispensed which includes a positive stop mechanism movable between xe2x80x9creadyxe2x80x9d and xe2x80x9cstopxe2x80x9d positions as the drive roller rotates. Rotational movement of the drive roller is at least in part responsible for movement of the mechanism to the stop position. Generally, the invention includes a rotatable drive roller stop support structure linked for rotational movement with the drive roller. A movable drive roller stop is mounted with respect to the support structure for movement between the ready position and the stop position. Finally, a drive roller stop engagement member is mounted with respect to the frame and is positioned to engage the drive roller stop when the device is in the stop position. The movable stop is positioned at the stop position as the drive roller rotates as hereinafter described.
Highly preferred forms of the stop support structure take the form of a toothed wheel which is linked to the drive roller and rotatable therewith. The drive roller stop is mounted with respect to the wheel. This highly preferred embodiment further includes a wheel stop positioned to ride over the teeth when the drive roller is rotated in a first direction and to engage a tooth when the drive roller is rotated in a second direction thereby limiting bidirectional movement of the drive roller. It is highly preferred that the teeth are configured to permit limited movement of the wheel in the second direction once the wheel moves to the stop position so that the drive roller stop can return to the ready position.
This highly preferred embodiment further includes biasing apparatus mounted to bias the drive roller toward rotation in at least the second direction. A spring is the most preferred form of biasing apparatus for use with the invention. Preferably, the spring is a tension spring and the spring has one end secured to an anchor and a second end secured with respect to the wheel. The preferred spring is loaded as the wheel moves to the stop position and, after reaching the stop position, the spring rotates the wheel in the second direction until engagement of a tooth with the wheel stop.
The most highly preferred forms of the drive roller stop comprise a stop member positioned for movement with respect to the wheel and at least one stop member constraint: surface positioned with respect to the wheel for limiting movement of the stop member. In the stop position, the stop member moves to a position where it contacts the engagement member which preferably is a post. It is most highly preferred that the stop member is mounted for back-and-forth movement along an axis forming a wheel radius. In this arrangement, the stop member extends outwardly to engage the post thereby positively stopping drive roller rotation in the first direction.
Highly preferred forms of the constraint surface(s) comprises a pocket positioned in the toothed wheel. The pocket has walls forming an opening for receiving the stop member and for constraining movement of the stop member therebetween. When the preferred pocket comprises the constraint surface, the stop member moves along the pocket walls in a reciprocal motion outward to the stop position and, after reaching the stop position, moves inward to the ready position.
Restraint structure may be provided to ensure that the stop member does not slide completely; away from the support structure. In the case of the preferred pocket, such restraint structure can optionally consist of a restraint surface along the stop member and an abutting restraint surface along the pocket. The restraint surfaces coact to limit outward movement of the stop member.
Other structure, such as cutter apparatus for cutting the web material into separate sheets of predetermined length, may be provided consistent with the disclosure herein. Preferably, such cutting results in partial perforation, rather than complete cutting, so that the web will remain intact until the stop mechanism is engaged and so that the energy from the pulling action can be used to power the dispenser.